Rotylenchulus reniformis is one of the most important nematode pests of cotton. Currently, no cotton cultivar resistant cotton cultivar to this pest is available. In the Framework of a breeding program ... [more ▼]

Rotylenchulus reniformis is one of the most important nematode pests of cotton. Currently, no cotton cultivar resistant cotton cultivar to this pest is available. In the Framework of a breeding program aiming at producing cotton genotype resistant to this nematode, a R. reniformis resistance evaluation protocol based on egg inoculation, extraction and counting, has been established. Two environment conditions (growth chamber and greenhouse), four sieves (75, 50, 20 and 10 µm), three doses of inoculum (1,500 ; 3,000 and 6,000 eggs), and five durations of infestation (20, 30, 40, 50 and 60 days after inoculation) have been tested. The growth chamber programmed to provide 12h of light, 55% - 60% relative humidity and 30 - 26°C day-night air températures revealed to be adequate. The NaOCI (sodium hypochloride) - blender - sieving - centrifugation - flotation method, using 75-µm and 20-µm sieves, kaolin powder and MgSO4 (magnesium sulfate) solution (specific gravity 1.18) proved to be suitable for effective R. reniformis egg extraction (from roots) and counting. Inoculation of 6,000 eggs per seeding and 60 days duration of infestation seemed to be sufficient dose and period for a reliable resistance evaluation. The protocol developed has been tested on known susceptible and resistant cotton génotypes : G. hirsutum L (main cultivated species through the world, susceptible), G. thurberi Tod. (wild cotton species, moderately susceptible) G. longicalyx Hutch. and Lee (wild cotton species, very resistant). The results obtained were in accordance with the response expected from the génotypes tested, proving the reliability of the evaluation procedure developed. [less ▲]

Entire plants were regenerated from nodes explants of Jatropha curcas L. following a procedure of bud aggregate induction on MS (Murashige and Skoog) medium supplemented with 25 mg.l-1 citric acid, 12.2 mg.l-1 adenine sulfate, 15 mg.l-1 L-arginine, 2.46 µM IBA (indole-3-butyric acid), 30 g.l-1 sucrose and 7 g.l-1 of agar, and enriched with different balances of BA (benzyladenine) and L glutamine. The histological studies performed on aggregates showed that the buds result from both the development of axillary buds and adventitious budding starting from underlying tissues of the explant. The culture medium containing 6.65 µM BA and 25 mg.l 1 L-glutamine gave the best results with an average of 64 buds per aggregate after three weeks for all accessions tested. The buds developed into shoots when placed in a MS medium supplemented with 2.21 µM BA, 5.70 µM IAA (indole-3-acetic acid) and 15 mg.l-1 L arginine. These shoots were isolated and then rooted in MS containing 2.46 µM of IBA, 2% sucrose and 0.7% agar. The entire process took 13 weeks with a 98% survival rate in terms of plantlets acclimatization. We obtained a multiplication rate of 13 buds per explant and per subculture which is the double of those obtained in other recent works based on the micropropagation of J. curcas from node explants. This protocol is economically more profitable. [less ▲]

To regenerate adventitious shoots from the cotyledon proximal parts of Citrullus lanatus (Thunb.) Matsum. and Nakai ssp. mucosospermus (Fursa) oleaginous type, different concentrations of MS mineral elements, sucrose, 6-benzylaminopurine (BAP) and agar were tested. Shoot induction proved to depend on the interaction between levels of sucrose, BAP and MS mineral elements in the medium. The medium containing 3/2 strength of MS mineral elements, 35 g/l sucrose and 1 mg/l BAP solidified with 6 g/l agar allowed the production of numerous shoots without a callus phase. After 3 weeks of culture, 76.7% of the cotyledon proximal parts induced shoots with an average of 12.26 shoots per explant and a mean shoot length of 17.13 mm. The induced shoots were directly rooted and thus complete plants ready for acclimatization were obtained using a two steps procedure. Depending on the genotype, the shoot induction from cotyledon proximal parts ranged from 54% to 96%. Rooted plantlets were acclimatized and transferred to field, where they grew well, developed flowers and fruits like seeded plants. The assessment of the genetic stability of the in-vitro-regenerated plantlets by means of an Amplified Fragment Length Polymorphism (AFLP) analysis with the combination of 5 primers revealed no differences between regenerated plantlets and mother plants. [less ▲]

The aim of this study was to describe the embryos abortion process and the inheritance of the embryos abortion trait in Phaseolus vulgaris plants deficient in seed development. These plants were isolated ... [more ▼]

The aim of this study was to describe the embryos abortion process and the inheritance of the embryos abortion trait in Phaseolus vulgaris plants deficient in seed development. These plants were isolated within the second generation of an ethyl methanesulfonate (EMS) TILLING population of P. vulgaris cv. 'BAT93'. Mutant embryos show abnormalities mainly in suspensors, shoot apical meristem (SAM) and cotylédons from the globular to the cotyledon stages and abort before maturity compared to those observed in wild-types samples. Mutant embryos show also hyperhydricity and contain low amount of chlorophyll. Genetic analyses of F1, F2 and F3 populations from the crosses carried out between the mutagenized plants with aborting embryos and the wild-type plants indicated that the embryo abortion phenotype is maternally inherited and controlled by a single recessive gene. These Phaseolus mutant plants with aborting embryos constitute a valuable material for plant embryogenesis studies. [less ▲]

Pythium root rot constitutes a highly damaging constraint on the common bean, Phaseolus vulgaris L., grown in several areas of Eastern and Central Africa. Here, this food legume is cultivated intensively under poor conditions of crop rotation due to the exiguity of the land in the region. Yield losses of up to 70 % in traditional local bean cultivars have been reported in Kenya and Rwanda. In this study, a detailed analysis of the biology and diversity of the Pythium genus was carried out in order to understand the mechanisms leading to the development of the disease. Various control methods for reducing the damage provoked by this disease were analyzed. [less ▲]

Objectives : the study was conducted to determine the optimum age of the fruit at harvest and to evaluate the effect of pre-storage and fermentation on the seeds'agronomic performance of oleaginous ... [more ▼]

Objectives : the study was conducted to determine the optimum age of the fruit at harvest and to evaluate the effect of pre-storage and fermentation on the seeds'agronomic performance of oleaginous Lagenaria siceraria. Methodology and results : Fruit of the "round-fruited" and "blocky-fruited", two cultivars of the species, were harvested at 3 different ages (30, 40 and 50 days after anthesis (DAA)). These fruits were pre-stored during 0,30 and 60 days after harvest (DAH), and then their seeds were fermented for 0,5 and 10 days. Seed viability (germination percentage and germination speed index) and seedlings vigor (emergence percentage, emergence speed index, seedling shoot length and seedling dry weight) were significantly (P< 0.001) influenced by each of the three factors. Following the positive interaction of these factors, the best viability and the most vigorous seedlings were obtained with seeds from fruits tardily harvested (50 DAA), pre-stored for a long time (60 DAH) and longer fermented (10 days). The simultaneous variation of the fruit wet weight and the seed color, dry weight and moisture content with their viability and the seedlings vigor indicates that these four parameters can be used as indicators of both cultivars maturity. Conclusions and application of findings : The results suggest that in deaginous L siceraria, fruits must be harvested 50 DAA, pre-stored up to 60 DPA. Good agronomic quality seeds must have yellow-orange color and be fermented up to 10 days. [less ▲]

in Journal of the Science of Food and Agriculture (2011), 91(11), 2073-2080

BACKGROUND: The stage of fruit ripeness at the time of harvest determines the final quality of ripe fruit. In this study, changes in the chemical composition of seed kernels from the oleaginous gourd ... [more ▼]

BACKGROUND: The stage of fruit ripeness at the time of harvest determines the final quality of ripe fruit. In this study, changes in the chemical composition of seed kernels from the oleaginous gourd Lagenaria siceraria (Molina) Standl. during maturation were evaluated to determine the best time to harvest the berries. Two cultivars (round and oval berry) were studied at three maturation stages (30 and 50 days after fruit set (DAFS) and complete plant whiteness (CPW)). [less ▲]

The extension of Jatropha curcas L. cultivation as a biofuel feedstock species requires the distribution of a very large number of plants to the producers in a very short period of time. These plants have ... [more ▼]

The extension of Jatropha curcas L. cultivation as a biofuel feedstock species requires the distribution of a very large number of plants to the producers in a very short period of time. These plants have to be able to give a high oil yield and be morphologically and phenotypically homogeneous to facilitate cultural operations. If high oil content can be obtained by varietal selection, the achievement of homogeneous material passes by the in vitro propagation. Various methods of mass production of plant material by axenic culture have been published. This study reviews the protocols published for in vitro propagation of J. curcas and discusses their applicability to an industrial scale. [less ▲]